Middle age athletes who are not used to exercising commonly get Achilles tendonitis, often because they fail to warm up and stretch prior to, and after, exercising. Their muscles may be tight due to inactivity and therefore can not withstand the stress of vigorous exercise right from the start. Runners that participate in middle to long distance event may develop problems with their Achilles tendon as the tendons will fatigue as the run time increases. Athletes who participate in sports such as basketball, tennis, and dancing in which there may be sudden starts and stops or a lot of jumping are also prone to Achilles tendon injuries.